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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,423 records · Page 79
All sourcesNASA NTRSDOE OSTI
NASA NTRS1987

The global residual mean circulation in the middle atmosphere for the northern winter period

The residual mean circulation (rmc) has been calculated from the transformed thermodynamic equation using LIMS (Limb Infrared Monitor of the Stratosphere) data for the 100-0.1 mb region. For discussion, it has been divided into two components: the diabatic circulation, associated with the diabatic heating, and the transient circulation, more directly connected to eddy activity. The slowly varying diabatic circulation reveals an equator-to-pole circulation at lower levels in the stratosphere, usually overlain by a summer-to-winter pole circulation. However, there are strong seasonal variations, so that the pole-to-pole circulation fills the entire region at the December solstice, while the equator-to-pole circulation extends to above 0.1 mb at the equinoxes. The transient circulation is characterized by rapid variations and small vertical and horizontal scales. Though generally smaller than the diabatic circulation, it can dominate in the lower stratosphere during disturbed conditions. This circulation is consistent with the transformed momentum equation in the lower stratosphere (where drag is expected to be small) during undisturbed periods. It suggests a large drag due to small-scale waves (such as gravity waves) in the mesosphere, although the magnitudes are uncertain. The downward propagation of the semiannual oscillation causes the rmc in the tropics to vary, and it is capable of creating the equatorial water vapor maximum above 10 mb.

Gille, John C.↗
NASA NTRS1988

Examination of Martian sedimentary rocks to understand possible paleo-ocean and its age

It is well known that the terrestrial marine sediments have large cerium anomaly on their chondrite-normalized REE pattern. Siliceous shale and calcaleous sediments have negative Ce-anomaly. Ferromanganese nodule have positive or negative Ce-anomaly. The Ce-anomaly is considered to be a result of tetravalent state of cerium rather than common trivalent. Ferromanganese nodule which formed under reducing condition has negative Ce-anomaly. Then, combined study of Ce-anomaly with Ce isotopes is expected to play an important role in geochemistry. La-138 decays to Ce-138 and Ba-138 with a total half life of about 1 x 10 to the 11th years. Cerium anomalies (positive or negative) are expected in Martian paleo-ocean and in sediments as observed in the terrestrial environment. A list of things to be examined is given.

Tanaka, T.↗
NASA NTRS1989

Numerical studies of incompressible flow around delta and double-delta wings

The subject has been jointly investigated at NASA Langley Research Center and the Aerodynamisches Institut of the RWTH Aachen over a substantial period. The aim of this investigation has been to develop numerical integration procedures for the Navier-Stokes equations - particularly for incompressible three-dimensional viscous flows about simple and double delta wings - and to study the low speed flow behavior, with its complex vortex structures on the leeward side of the wing. The low speed flight regime poses unusual problems because high incidence flight conditions may, for example, encounter symmetric and asymmetric vortex breakdown. Because of the many difficulties to be expected in solving the problem, it was divided into two - analysis of the flow without vortex breakdown and analysis of the breakdown of isolated vortices. The major results obtained so far on the two topics are briefly described.

Krause, E.↗
NASA NTRS1992

A Mars Environmental Survey mission concept

The Mars Environmental Survey, or 'MESUR' mission presently discussed proceeds by emplacing a network of small stations on the Martian surface. These stations will determine the global seismicity of the planet, to facilitate studies of its internal structure; they will also broaden knowledge of atmospheric and surface meteorology conditions and determine the major and minor elements of surface soil and rock compositions. They are also expected to deepen understanding of Mars' middle and upper atmosphere. Attention is given to the design and operations of the MESUR lander.

Hubbard, G. S.↗
NASA NTRS1999

Investigations of Remote Plasma Irregularites by Radio Sounding: Applications of the Radio Plasma Imager on IMAGE

The Radio Plasma Imager (RPI) on the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) mission operates like a radar by transmitting and receiving coherent electromagnetic pulses. Long-range echoes of electromagnetic sounder waves are reflected at remote plasma cutoffs. Thus, analyses of RPI observations will yield the plasma parameters and distances to the remote reflection points. These analyses assume that the reflecting plasma surfaces are cold and are sufficiently smooth that they effectively behave as plane mirrors to the incoming sounder waves, i.e., that geometric optics can be used. The RPI will employ pulse compression and spectral integration techniques, perfected in ground-based ionospheric digital sounders, in order to enhance the signal-to-noise ratio in long-range magnetospheric sounding. When plasma irregularities exist in the remote magnetospheric plasmas that are being probed by the sounder waves, echo signatures may become complicated. Ionospheric sounding experience indicates that while topside sounding echo strengths can actually be enhanced by the presence of irregularities, ground-based sounding indicates that coherent detection techniques can still be employed. In this paper we investigate the plasma conditions that will allow coherent signals to be detected by the RPI and the signatures to be expected, such as scattering and plasma resonances, in the presence of multi-scale irregularities, may possibly have on RPI signals. Sounding of irregular plasma structures in the plasmasphere, plasmapause and magnetopause are also discussed.

Fung, Shing F.↗
NASA NTRS2001

A 3-D Magnetic Analysis of a Stirling Convertor Linear Alternator Under Load

The NASA Glenn Research Center (GRC), the Department of Energy (DOE), and the Stirling Technology Company (STC) are developing Stirling convertors for Stirling Radioisotope Power Systems (SRPS) to provide electrical power for future NASA deep space missions. STC is developing the 55-We Technology Demonstration Convertor (TDC) under contract to DOE. Of critical importance to the successful development of the Stirling convertor for space power applications is the development of a lightweight and highly efficient linear alternator. This paper presents a 3-dimensional finite element method (FEM) approach for evaluating Stirling convertor linear alternators. The model extends a magnetostatic analysis previously reported at the 35th Intersociety Energy Conversion Engineering Conference (IECEC) to include the effects of the load current. STC's 55-We linear alternator design was selected to validate the model. Spatial plots of magnetic field strength (H) are presented in the region of the exciting permanent magnets. The margin for permanent magnet demagnetization is calculated at the expected magnet operating temperature for the near earth environment and for various average magnet temperatures. These thermal conditions were selected to represent a worst-case condition for the planned deep space missions. This paper presents plots that identify regions of high H where the potential to alter the magnetic moment of the magnets exists.

Geng, Steven M.↗
NASA NTRS2003

Balance in a rotating artificial gravity environment

When subjects stand at the center of a fully enclosed room that is rotating at constant velocity, their natural postural sway generates Coriolis forces that destabilize their center of mass and head. We quantitatively assessed how exposure to constant velocity rotation at 10 rpm affected postural control. Twelve subjects stood in a heel-to-toe stance in the rotating room. Each test session involved three phases: (1) pre-rotation, (2) per-rotation, and (3) post-rotation. In each phase, subjects were tested in both eyes open and eyes closed conditions. Four measures were used to characterize center of mass movement and head movement: mean sway amplitude, total power, mean power frequency, and frequency of maximum power. Each measure was computed for anterior-posterior and medial-lateral sway. Both anterior-posterior and medial-lateral head and center of mass sway during rotation had significantly greater mean sway amplitude and total power compared with pre- and post-rotation values. Mean power frequency and frequency of maximum power were little affected. Eyes open conditions were significantly more stable in all test phases than eyes-closed, but vision did not completely suppress the effects of rotation. The greatest effect of rotation was in the eyes-closed condition with mean sway amplitude and total power increasing more than twofold. Inverted pendulum sway was maintained in all phases of both test conditions. No aftereffects of rotation were present after the four 25-s exposures each subject received. We expect that with longer exposure periods and with active generation of body sway subjects would both adapt to rotation and exhibit post-rotary aftereffects.

NASA Discipline Neuroscience↗
NASA NTRS2005

Seismic study of the solar subsurface based on robust time-distance inferences

Progress on this project has been constrained by the unexpected death of my long time collaborator, Peter Nisenson. I worked on several other projects as a collaborator of Pete, who became seriously ill in November 2003. He continued to work as much as his condition allowed him, but his condition worsened, and Pete died on June 21 2004. I ended up a year ago with an expected substantial workload increase. I had no choice but to re-prioritize my efforts, and one other project in which Pete would have taken a substantial role, has in the past year taken an unexpected large fraction of my time.

Korzennik, Sylvain G.↗
NASA NTRS2016

Steepening of Waves at the Duskside Magnetopause

Surface waves at the magnetopause flanks typically feature steeper, i.e., more inclined leading (antisunward facing) than trailing (sunward facing) edges. This is expected for Kelvin-Helmholtz instability (KHI) amplified waves. Very rarely, during northward interplanetary magnetic field (IMF) conditions, anomalous inverse steepening has been observed. The small-scale tetrahedral configuration of the Magnetospheric Multiscale spacecraft and their high time resolution measurements enable us to routinely ascertain magnetopause boundary inclinations during surface wave passage with high accuracy by four-spacecraft timing analysis. At the dusk flank magnetopause, 77%/23% of the analyzed wave intervals exhibit regular inverse steepening. Inverse steepening happens during northward IMF conditions, as previously reported and, in addition, during intervals of dominant equatorial IMF. Inverse steepening observed under the latter conditions may be due to the absence of KHI or due to instabilities arising from the alignment of flow and magnetic fields in the magnetosheath.

Plaschke, F.↗
NASA NTRS2017

Aerodynamic Coefficients from Aeroballistic Range Testing of Deployed- and Stowed-SIAD SFDT Models

This report documents a ballistic-range test campaign conducted in 2012 in order to estimate the aerodynamic stability characteristics of two configurations of the Supersonic Flight Dynamics Test (SFDT) vehicle prior to its initial flight in 2014. The SFDT vehicle was a test bed for demonstrating several new aerodynamic decelerator technologies then being developed under the Low-Density Supersonic Decelerator (LDSD) Project. Of particular interest here is the Supersonic Inflatable Aerodynamic Decelerator (SIAD), an inflatable attached torus used to increase the drag surface area of an entry vehicle during the supersonic portion of the entry trajectory. Two model configurations were tested in the ballistic range: one representing the SFDT vehicle prior to deployment of the SIAD, and the other representing the nominal shape with the SIAD inflated. Both models were fabricated from solid metal, and therefore, the effects of the flexibility of the inflatable decelerator were not considered. The test conditions were chosen to match, as close as possible, the Mach number, Reynolds number, and motion dynamics expected for the SFDT vehicle in flight, both with the SIAD stowed and deployed. For SFDT models with the SIAD stowed, 12 shots were performed covering a Mach number range of 3.2 to 3.7. For models representing the deployed SIAD, 37 shots were performed over a Mach number range of 2.0 to 3.8. Pitch oscillation amplitudes covered a range from 0.7 to 20.6 degrees RMS. Portions of this report (data analysis approach, aerodynamic modeling, and resulting aerodynamic coefficients) were originally published as an internal LDSD Project report [1] in 2012. In addition, this report provides a description of the test design approach, the test facility, and experimental procedures. Estimated non-linear aerodynamic coefficients, including pitch damping, for both model configurations are reported, and the shot-by-shot trajectory measurements, plotted in comparison with calculated trajectories based on the derived non-linear aerodynamic coefficients, are provided as appendices. Since the completion of these tests, two full-scale SFDT flights have been successfully conducted: one in June 2014 [2, 3], and one in June 2015 [3].

Ground Test↗
NASA NTRS2019

Evaluation Studies of a 800W Solid Oxide-Based Fuel Cells Stack for Electrical Power in Aviation

As both NASA and the aeronautics industry recognize the need for higher fuel efficiency and lower carbon emissions in both commercial airline and private aviation applications, development of all-electric or hybrid electric aircraft have garnered renewed interest in the aviation community. For the particular example of the hybrid-electric option, the solid oxide fuel cell (SOFC) is an attractive option for the power source, due to its potential to utilize aviation fuels thereby having minimal impact to aviation infrastructure. SOFC stack performance depends upon many factors, one of the most important is the way the oxidant and fuel gases are delivered to the fuel cells. System modeling of various aircraft configurations for FUELEAP (Fostering Ultra-Efficient, Low-Emitting Aviation Power) point to the need to operate SOFC stacks at high current densities. This creates challenges in the thermal profile of the stacks with potential to create large thermal gradients and hot spots. This study investigates two types of commercial solid oxide fuel cell stacks, the cross flow and co-flow gas designs, both convectively cooled with cathode air. High fuel utilization factors were also employed under varying electrical loads expected from the demands of flight. In addition, performance, range of operation and endurance were investigated under conditions of high current loads and thermal cycling. Evaluations include the study of gas kinetic using electrochemical spectroscopy. Testing took place at the facilities of NASA Glenn using a commercial test system (FuelCon AG, Magdeburg Germany). These studies are crucial to the Glenn Research Center's ability to conduct research, evaluation and development of the next-generation SOFC based stacks for cutting-edge energy technologies for aerospace applications. This study supports NASA's Convergent Aeronautics Solutions' (CAS) FUELEAP project.

Goldsby, Jon C.↗
NASA NTRS2019

Plasma environment effects on K lines of astrophysical interest II. Ionization potentials, K thresholds, radiative rates, and Auger widths in Ne- through He-like iron ions (Fe xvii – Fe xxv)

Aims. In the context of accretion disks around black holes, we estimate plasma-environment effects on the atomic parameters associated with the decay of K-vacancy states in highly charged iron ions, namely Fe XVII – Fe XXV. Methods. Within the relativistic multiconfiguration Dirac–Fock (MCDF) framework, the electron–nucleus and electron–electron plasma screenings were approximated with a time-averaged Debye–Hückel potential. Results. Modified ionization potentials, K thresholds, wavelengths, radiative emission rates, and Auger widths are reported for astrophysical plasmas characterized by electron temperatures and densities in the ranges 10^5 − 10^7 K and 10^18 − 10^22 per cu.cm, respectively. Conclusions. We conclude that the high-resolution microcalorimeters on board future X-ray missions such as XRISM and ATHENA are expected to be sensitive to the lowering of the iron K edge due to the extreme plasma conditions occurring in accretion disks around compact objects.

J. Deprince↗
NASA NTRS1990

Solar array arcing in plasmas

Solar cells in space plasma conditions are known to arc into the plasma when the interconnects are at a negative potential of a few hundred volts, relative to plasma potential. For cells with silver-coated interconnects, a threshold voltage for arcing exists at about -230 V, as found in both ground and LEO experiments. The arc rate beyond the threshold voltage depends nearly linearly on plasma density, but has a strong power-law dependence on voltage, such that for small increments in operating voltage there is a large increment in arc rate. The arcs generate broadband radio interference and visible light. In ground tests, interconnects have been damaged by arcs in cells having insufficient isolation from a source of high current. Models for the arcs are highly dependent on the choice of interconnect conductor material exposed to the plasma and possibly on the geometry and choice of adjacent insulator material. Finally, new technology solar cells use copper for the cell interconnects, a material which may have a lower arcing threshold voltage than silver. It is expected, from ground tests of simulated solar cells, that any junction of conductor and insulator exposed to space plasma conditions will arc into the plasma at a few hundred volts negative potential, relative to the local plasma.

Ferguson, Dale C.↗
DOE OSTI2025

Coupling to rotational manifolds to improve gas-phase pump–probe spectroscopic models

The physical picture of gas-phase optical transitions is normally presented as an isolated two-level system balanced by upward and downward processes. Isolated models assume a phenomenological treatment of collisional dephasing but do not strictly account for collisional population exchange with the rotational baths. While this assumption is valid under low-intensity conditions, where excitation is rate-limiting, isolated models can deviate from Beer’s Law at sufficient pressures and monochromatic intensities when both collisional broadening and power broadening are comparable to (or greater than) lifetime broadening, which are not uncommon conditions for cavity enhanced spectroscopies in the mid-IR spectral range. Although this problem has been addressed by rate-equation models for linear absorption measurements, a general treatment for multi-level quantum mechanical models suitable for non-linear absorption measurements (two-photon/two-color/pump–probe) is lacking. Isolated models require physical parameter inputs that disagree with expected values by at least an order of magnitude. These non-physical models undermine the ability to predict non-linear signal strengths under untested conditions and thereby limit the potential to optimize the sensitivity of non-linear spectroscopies and to expand their analytical applications (e.g., new analytes and/or buffer gases, changes in cavity free-spectral-range, changes in intracavity powers or wavelengths, and accurate investigation of physical phenomena). In this study, we derive bath-coupled models for gaseous pump–probe spectroscopy by application of the quantum Lindblad equation and detailed balance. Bath-coupled models are shown to fit data consistently across variations in intensity and agree with all physically expected values.

Cavity ring-down spectroscopy↗
NASA NTRS1982

Bolt clampup relaxation in a graphite/epoxy laminate

A simple bolted joint was analyzed to calculate bolt clampup relaxation for a graphite/epoxy (T300/5208) laminate. A viscoelastic finite element analysis of a double-lap joint with a steel bolt was conducted. Clampup forces were calculated for various steady-state temperature-moisture conditions using a 20-year exposure duration. The finite element analysis predicted that clampup forces relax even for the room-temperature-dry condition. The relaxations were 8, 13, 20, and 30 percent for exposure durations of 1 day, 1 month, 1 year, and 20 years, respectively. As expected, higher temperatures and moisture levels each increased the relaxation rate. The combined viscoelastic effects of steady-state temperature and moisture appeared to be additive. From the finite-element analysis, a simple equation was developed for clampup force relaxation. This generalized equation was used to calculate clampup forces for the same temperature-moisture conditions as used in the finite-element analysis. The two sets of calculated results agreed well.

Shivakumar, K. N.↗
NASA NTRS2009

The Development and Implementation of a Cryogenic Pressure Sensitive Paint System in the National Transonic Facility

The Pressure Sensitive Paint (PSP) method was used to measure global surface pressures on a model at full-scale flight Reynolds numbers. In order to achieve these conditions, the test was carried out at the National Transonic Facility (NTF) operating under cryogenic conditions in a nitrogen environment. The upper surface of a wing on a full-span 0.027 scale commercial transport was painted with a porous PSP formulation and tested at 120K. Data was acquired at Mach 0.8 with a total pressure of 200 kPa, resulting in a Reynolds number of 65 x 106/m. Oxygen, which is required for PSP operation, was injected using dry air so that the oxygen concentration in the flow was approximately 1535 ppm. Results show qualitative agreement with expected results. This preliminary test is the first time that PSP has been successfully deployed to measure global surface pressures at cryogenic condition in the NTF. This paper will describe the system as installed, the results obtained from the test, as well as proposed upgrades and future tests.

Watkins, A. Neal↗
DOE OSTI2023

Cesium Removal from 5.5 and 7.0 M Na AP-105 Using Crystalline Silicotitanate

The Tank Side Cesium Removal (TSCR) system, currently operational by Washington River Protection Solutions LLC (WRPS), prepares initial low-activity Hanford waste tank supernate feeds for the Hanford Waste Treatment and Immobilization Plant (WTP) Low-Activity Waste (LAW) Facility. In addition to entrained solids removal from the supernate, the primary goal of TSCR is to remove cesium-137 ( 137 Cs) by ion exchange, allowing contact handling of the liquid effluent product at the WTP as governed by a waste acceptance criterion (WAC). Specific to 137 Cs, this requirement is < 3.18E-5 Ci 137 Cs/mole of Na. Crystalline silicotitanate (CST) ion exchange media, manufactured by Honeywell UOP, LLC (product IONSIVTM R9140-B), has been selected as the ion exchange media for TSCR. CST is a non-elutable inorganic material that has demonstrated robust chemical, physical, and radiation tolerance while maintaining functionality. However, testing to date on actual tank waste samples has been limited to Na concentrations between 5 and 6 M Na (Fiskum et al. 2019a, 2021b and Westesen et al. 2021a, 2021b, 2022) while actual tank conditions can reach upwards of 9 M Na. Testing with feed from Hanford tank AP-105 incorporated testing at both 5.5 and 7 M Na in order to evaluate the impact of Na concentration on volume of waste processed before reaching the WAC. A 6-L volume of 5.5 M Na AP-105 and an 8-volume of 7 M Na AP-105 was processed through the Radioactive Waste Test Platform system, established at Pacific Northwest National Laboratory to support small-scale waste qualification efforts. The columns consisted of 6- to 9-mL CST beds (CST Lot 2002009604, sieved to screen out >30-mesh particles) placed in 1.5-cm-inner-diameter columns. Feed was processed at 1.9 bed volumes (BV) per hour; the flowrate, in terms of contact time with the CST bed, matched the expected flowrate at TSCR. Table S.1 and Figure S.1 summarize the measured AP-105 Cs load performance for each feed condition.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Artificial Intelligence Application to D and D - 20492

As aging facilities across the DOE complex await decommissioning, there is an ongoing need to understand any changes in the structural conditions. Many of these facilities were built over 50 years ago and, in some cases, these facilities have gone beyond the expected operational lifetime. Many facilities have been placed in a state of 'cold and dark,' sitting unused and awaiting decommissioning. Especially challenging are the aging facilities that provide unique operational/production capabilities to support critical DOE missions and cannot be shut down. In any of these scenarios, the structural integrity of these facilities may become compromised as time passes. It is critical that adequate inspections be performed on a continual basis and that the data collected undergoes sufficient analysis to support timely identification of any new or worsening structural issues as well as prompt needed maintenance and repairs to maintain the facilities in a safe condition. In recent days, Artificial Intelligence (AI) [1] and its application to various domains are growing at fast speed. FIU is performing research in this area and exploring the associated technologies to solve nuclear decommissioning problems. Artificial intelligence refers to the capability of a program to autonomously act, react and adapt to the working environment. AI enables the machine to behave like humans and perform the cognitive functions such as 'learning' and 'problem solving'. AI systems gradually moving from traditional approaches (algorithms and expert systems) towards more efficient and advanced technologies (machine learning [1] and deep learning [2] [3]). AI is the study of algorithms and statistical models that is being used by computers to perform specific tasks without using explicit instructions. FIU is working to develop a pilot-scale infrastructure to implement structural health monitoring using AI technologies with focus on machine learning, deep learning. This research is focused on Computer Vision/Image Classification area of AI applications. This can also be expanded to other areas of AI related to Object Recognition and Character Recognition in images. In addition to utilizing existing data sets, FIU will collect and investigate image and video data using FIU test-bed mockups to monitor structural health of the facility. Resulting data will be processed and analyzed using machine learning/deep learning technologies. The proposed pilot system is intended to serve as a starting point to engage the DOE field sites on related data sets and their decision making needs. It is anticipated that proposed machine learning/deep learning technologies can be effectively employed using anomaly detection to solve EM challenges in surveillance and maintenance of the D and D facilities. FIU will work with research stakeholders to identify applications at various sites and other DOE facilities. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗